Spark-plug



H. C. SUCKERT.

SPARK PLUG.

APPLICATION HLED Nov. 18, 1916.

Patented Dec. 28, 1920.

2 $HEETS-SHEET I. lllllllllllllv Il r I UNITE HAROLD C. SUCKERT, 0F NEW YQFEtK, N. i".

SPARE-FLUG.

Specification of Letters Patent.

Patented Dee. 28, 1924).

Application filed November 15, 1916. Serial No. 131,988.

. and State of New York, have invented certain new and useful Improvements in Spark-Plugs, or" which the following is a specification.

This invention relates to improvements in spark plugs for internal combustion engines,

and has for its principal object the provision of a spark "plug in which the porcelain insulator is protected from accidental breakage by being struck by tools used by me chanics in repair work.

A further object of the invention is the provision of a spark plug having, an insulator protector so formed that oil orwater cannot accumulate Within the protector and create a short circuit'in the ignition system.

Another object of the invention is the provision of a spark plug having an insulatorprotecting casing of such construction that the plug may be readily screwed into the engine cylinder and the conducting wire readily connected with the central electrode.

Tn the drawings Figure 1 is a vertical sectional view of a spark plug showing one embodiment of the invention;

Fig. 2 a side elevation of the form of plug shown in Fig. 1;

Figs. 3 and 4c vertical sectional views of sli htly modified forms of the plug shown in igs. 1 and 2;

Fig. 5 a side elevation ofthe plug shown I in Fig. 4;

Figs. 6, 'Z and 8 are vertical sectional views of modified forms of spark plugs emhodying the invention;

Fig. 9 is a side elevation of the plug shown in Fig. 8;

Fig. 10 is a vertical sectional view of a spark plug embodying the invention, in which the porcelain insulator and central electrode are wholly inclosed within a waterproof protecting casing;

Fig. 11 is a side e evation of the plug shown in Fig. 10;

Fig. 12 is a vertical sectional view of a plug embodying the invention, in which theinsulator and electrode are wholly inclosed within at protecting casing; and n Fig. 13 is a side elevation of the form of plug shown in Fig. 12.

Referring to the embodiment of the invention shown in Figs. 1 and 2 of the drawings 1 designates the porcelain insulator having an axial bore 0r passage through which the usual electrode 2 passes. The insulator 1 has an enlarged portion 3 intermediate its ends which is seated on the annular shoulder a in the shell or nipple 5.

The shell or nipple 5 has a reduced screwthreaded portion 6 adapted to be screwed into the engine cylinder in the wellknown manner, and an enlarged hexagonal portion 7 adapted to receive a wrench to screw the plug in the engine cylinder. The enlarged portion 7 of the shell 5 is screw-threaded internally as shown at 8, and a tubular insulator-protecting casing 9 is screwed therein and is adapted to bear upon the upper surface of the enlarged portion 3 of the insulator l and thus hold the insulator in place. The tubular protector 9 extends upwardly to a point substantially on a level with the upper end or" the insulator and the internal diameter of the protector that an air space is formed between the insulator and protector. The protector 9 is formed with a hexagonal enlargement 10 adapted to receive a wrench i'or screwing the protector into the shell 5. A. vent or drain opening 11 is formed in the walls of the protector to prevent an accumulation of oil or water within the protector that would result in short-circuiting the ignition system.

The modified form of plug shown in Fig. 3 of the drawings is constructed in the same manner as the plug shown in Figs. 1 and 2, except that the hexagonal portion 10 is eliminated and the upper portion of the protector 9 is enlarged and made of hexagonal form, as shown at 9.

Tn the form of plug shown in Figs; i and 5 the shell 5 is provided with a hexagonal wrench-receiving portion 7 and a reduced externally threaded cylindrical portion The protector 9 is formed with a hexagonal outer surface and is internally threaded at its lower end and screwed upon the threaded portion 8 of the shell. 'The protector is provided with an internal annular shoul der 12 adapted to bear upon. the upper face of the enlarged portion 3 of the insulator 1 to hold the insulator in place.

Tn the embodiment of the invention shown in ig. 6 a casing or shell having an enlarged portion 5 and an internally threaded portion 6, of substantially the same form as shown in Figs. 1, 2 and 3, is employed.

has a cylindrical screw-threaded bore 8. The shoulder a has a tapered seat 4:. The insulator 1 has a double taper, forming an enlarged portion 3 intermediate its ends.

The lower tapered portion of the insulator passes through the tapered seat 4* and is held against said seat by a nut 13 threaded into the bore 8 of the shell and having a tapered bore corresponding to the tapered upper portion of the insulator. The insu lator protector 9 is of hexagonal form in cross-section and is provided with an inwardly extending annular flange 14 at its lower end. This flange is clamped between the head 13 of the nut 13 and the upper end of the shell 5 when the parts are assembled. The protector 9 is provided with a suitable vent r drain opening 11.

Figs. 7, 8 and 9 show two embodiments of the invention in which the several parts are permanently connected together. In Fig. 7 the insulator 1 has an enlarged intermediate portion 3 with rounded sides and is preferably divided transversely into two sections, as shown. The under side of the portion 3 rests in a seat 4 formed inthe shell 5. The insulator is permanently secured in the shell by the tubular protector 9 The protector is formed of soft metal and its lower end forced down upon the upper face of the enlargement 3 and expanded into an annular groove 15 formed in the shell 5. The exterior of the enlarged portion 5 of the shell is of hexagonal contour to adapt it to receive a wrench. A slightly modified form of plug is shown in Figs. 8 and 9, the insulator 1 being locked in place by bending the upper end of the shell 5 over the upper face of the enlarged portion 3 of the insulator. The protector 9 is formed of soft metal and is tapered downwardly and outwardly. The large lower end of the protector embraces the enlarged hexagonal portion 5 of the shell and is made to conform to the contour thereof by any suitable means, so as to form a hexagonal wrench-receiving portion 9, as shown in Fig. 9.

In Figs. 10 and 11 a spark plug embodying the invention is shown in which the porcelain insulator, electrode and wire terminal are inclosed within an oil and water-proof casing which also serves to protect the insulator from accidental breakage. In this form of plug the insulator is cylindrical and has a. central longitudinal bore through which the electrode 2 passes. The insulator is formed with a plurality of annular grooves 1 and is securedin a tubular shell or casing 16 by annular ribs 17 formed by pressing the walls f the casing 16 inwardly into the annular grooves 1 in the insulator '1. The casing 16 is externally threaded at its lower end as shown at 6, to adapt it to be screwed into the usual aperture in the engine cylinder. l t-hexagonal wrench-receiving portion 7 is formed adjacent the upper end of the casing 16. The electrode 2 projects above the upper end of the porcelain insulator and is held in place by a nut 18 threaded on the projecting upper end thereof. A suitable washer 19 is preferably interposed between the nut 18 and the end of the insulator 1. The nut 18 is provided with an annular groove 18 and forms the upper terminal of the electrode 2. The upper end of the casing 16 is closed by a. cap 20 of insulating material. The conducting wire 21 passes through the cap 20 and is soldered or otherwise connected to a spring terminal clip 22 held in an annular recess formed in the cap 20. The clip 22 is provided with two or more downwardly and inwardly extending resilient arms 22 which.

are adapted to pass over the head of the nut 18 and spring into the annular groove 18 when the cap is placed on the upper end of the casing 16. The spring clip 22 thus serves to make the electrical connection between the wire 21 and electrode 2, and also holds the wireterminal-carrying cap 20 upon the upper end of casing 16. The cap 20 serves to prevent water oil or dirt from entering the interior of the casing 16. No vent or drain opening is necessary in this .form of plug.

Another embodiment of the invention is shown in Figs. 12 and 13. In this form of plug the insulator 1 is formed with an enlarged portion 3 and is permanently secured in the shell 5 by bending the upper end of the shell inwardly over the upper face ofthe enlarged portion 3 of the insulator. The lower face of the insulator rests upon the annular shoulder 4;. The shell 5 is provided with a hexagonal wrench-receiving portion 7 and is externally threaded at its lower end as shown at 6. The electrode 2 is held in place by a nut 23 threaded on the upper end thereof. The conducting wire 24 passes through a cap 25 of insulating material and the end of the wire is clamped between the nut 23 and the wall of a recess 26 formed in the under side of the cap. The cap is connected to the shell 5 by a stout coil spring 27, the convolutions of the spring adjacent each end thereof lying in spiral grooves 28 formed in the cap and shell. The coil spring 27 serves to hold the cap 25 tightly upon the nut 23, thus insuring a good electrical contact between the end of wire 24 and the nut on the electrode. The spring also serves as a protector for the insulator, preventing the insulator from being struck by tools during repair work on the engine. f

It will be seen that in the various embodiments of the invention shown and described the vitreous insulator is surrounded by a metallic casing which prevents the in sulator from being accidentally struck by wrenches or other tools employed in repairing or adjusting parts of the power plant. In spark plugs heretofore used substantially half of the porcelain or other vitreous insulator for the central electrode projects from the metal shell of the plug. The projecting ends of thesefrangible insulators are frequently cracked or broken off and the plug thus rendered useless. The present invention provides simple means for protecting the frangible insulator, of such construction that the current-conducting wire may be readily connected to the central electrode.

What I claim is:

1. A spark plug comprising a tubular casing having an externally threaded portion at one end and an angular wrench-receiving portion, an insulator Within said casing, means for holding the insulator in place, an electrode extending through the insulatorihaving a sparking terminal at one end, a nut threaded on the other end of said electrode and having an annular groove in its side walls, a cap of insulating material adapted to close the outer end of the casing, and a wire terminal carried by said cap comprising a resilient'metal clip adapted to engage in the groove in the nut to secure said cap to the casing and'make electrical contact with said electrode.

2. A spark plug comprising an imperforate casing, an insulator inclosed within the casing, an electrode extending through the insulator, a nut threaded on one end of the electrode, a closure cap for one end of the casing having an annular portion adapted to embrace the outer side of the casing and an internal flange adapted to abut against the end of the casing, and a resilient metallic wire-terminal clip carried by said cap and adapted to frictionally grip said nut.

3. A spark plug comprising a casing having an externally threaded portion at one end, an insulator within the casing, an electrode extending through the insulator, a nut threaded on one end of the electrode, a detachable closure cap having an annular portion adapted to closely. and frictionally engage one end of the casing, and a resilient metallic wire-terminal clip carried by said cap adapted to frictionally grip said nut.

4:. A spark plug comprising a-frangible insulator, metallic supporting and protecting means surrounding the insulator from end to end of the insulator, said insulator and metallic supporting means being pro vided with permanently interlocked complementary projecting and recessed portions, an electrode extending through the insulator a terminal-carrying member detachably held to one end of said supporting and protecting means, and a wire-terminal carried by said member.

5. A spark plug comprising an insulator having recesses in the outer side thereof, a casing surrounding the insulator from end to end of the insulator, an electrode extending through the insulator and having a sparking terminal at one end overhanging the adjacent 'end of the insulator, a nut threaded on the opposite end of the electrode said casing being formed with integral inwardly extending portions engaging in the recesses in the insulator for permanently holding the insulator in fixed relation with the casing, a closure detachably held to one end of the casing, and a wireterminal carriedby said closure adapted to engage the nut on the electrode.

6. A spark plug comprising a flangible insulator, an electrode extending through the insulator, and metallic protecting and supporting means inclosing the insulator substantially throughout the length of the insulator said insulator and metallic supporting means being permanently interlocked with each other by a circumferentially extending shoulder and groove connection.

7. A spark plug comprising a casing having an externally threaded portion at one end and an annular interior shoulder intermediate its ends, a closure detachably secured to the opposite end of the casing, a wire terminal carried by said closure and removable bodily therewith, an insulator within said casing formed with a circumferential groove into which the annular shoulder on the casing extends, and an electrode extending through the insulator and adapted to be electrically connected with said terminal by the act of attaching said closure to the casing.

In testimony whereof I hereunto afiix my signature.

HAROLD G. SUCKERT. 

